Rim Configuration is essentially the sharpness of the rim. The sharper the rim, the smaller the number. Here's how it's measured:

"The rim of the disc is held perpendicular to a contour gauge having 13 probes per cm (such as the Valued ST142). The rim of the disc is then pressed gradually into the gauge to a depth of 5 mm. The resulting movement of each affected probe is measured to the nearest 0.25 mm, and then totaled to produce the rim configuration rating. The ratings of three samples are determined, and the median score is used as the final rating."

So, the low height drivers don't engage as many probes in the gauge as say a Roc or Zephyr.

There's a minimum rim config but no maximum, so I assume that requirement is there to prevent discs from having rims so sharp that they could be highly dangerous both to the hand that throws them and anyone that might get hit by one?

No one knows exactly how sharp is too sharp. It's not like it was measured in some sort of safety test whatever that would be. I believe the Eclipse approved in 1989 may have been the benchmark for setting the minimum because its value is 26 which is still the allowable minimum.

probably about the same. I always thought the boss was pretty much the flippiest of the highspeed drivers, but is also the fastest, so it is speed stable for most. The boss reminds me of a fast Orc while the force reminds me of a fast starfire.

Its hard to say because Flashes are all over the place stability-wise. Surges don't really have a high speed turn when new unless you really push them past their cruising speed. Boss seems to flip inside of its cruising speed. In other words, the Boss is only flying its fastest while flipping, where the Surge only flips when thrown faster than it is meant to fly.